Multiple Endocrine Neoplasia
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How common is multiple endocrine neoplasia type 1?

The word “endocrine” refers to glands in the body that secrets hormones that are needed for the normal functioning of the body.

Multiple Endocrine Neoplasia (MEN) Syndrome is a disorder that causes either malignant or benign–cancerous or noncancerous–tumors to form and grow in several endocrine glands. The condition is caused by mutations in the genes of an individual and is a genetic/hereditary disease.

Multiple endocrine neoplasia syndrome is a rare disorder and consists of 3 types: Type1, Type2; 2A and 2B, and Type4. Type 1 and 2 are the most common types of MEN.

In this article, we will be discussing Type 1 of the MEN syndrome.

What Is Multiple Endocrine Neoplasia Type1 (MEN1)?

Also called “Wermer Syndrome”, MEN1 is a hereditary disorder that is characterized by the presence of tumors in the endocrine gland, which includes the parathyroid gland, islet cells of the pancreas, and pituitary gland. 

Sometimes, it can be seen in the adrenal gland called carcinoid tumor and in some part of the digestive tract like some part of the small intestine, and stomach. These tumors produce hormones in excess amount than what is needed in the body, resulting In a wide range of symptoms.

Such hormones that increase in production include:

  • Prolactin,  resulting in abnormal milk production and lack of menstrual flow in women, and low testosterone production in men.
  • Growth hormone, causing excessive growth of the jaw and other visceral tissues.
  • Adrenocorticotropic hormone, leading to excessive cortisol production by the adrenal glands.
  • Gastrin, causing stomach ulcers.
  • Glucagon, which results in diabetes mellitus, sometimes skin rash also.
  • Parathyroid hormone, resulting in high blood calcium (hypercalcemia) and sometimes, kidney stones.

However, these tumors are usually benign,  although research has shown approximately 1 in 3 cases of pancreatic neuroendocrine tumors and mediastinal neuroendocrine tumors turning cancerous.

It is estimated that about 1 in 30,000 people has MEN1. About 10% of people with MEN1 do not have a family history of the condition; they have a de novo (new) mutation in the MEN1 gene.


The Primary  Endocrine Tumours Which Makes Up MEN1 Includes:

  1. Primary hyperparathyroidism
  • Results in   overactivity of the parathyroid glands
  • Common at the age of 50 years. 
  • Increase in calcium levels in the blood and urine. 
  1. Pituitary tumors
  • Occurs in about 30–40% of people with MEN1 may develop pituitary tumors.
  • Produces excess prolactin resulting in abnormal milk production In women without pregnancy and can lead to impotence in men.
  • Could also lead to vision problems or headaches.
  1. Pancreatic neuroendocrine tumor sets)
    • Occurs in about  60% of people with MEN1.
    • Includes a tumor in the islet of the pancreas.
  • It could lead to Gastrinomas.  

Causes of Multiple Endocrine Neoplasia Type1 (MEN1)

The causes of MEN1 includes:

  • Genetic predisposition since it is a hereditary condition.

Mutation in the MEN1 gene. Recent studies have also shown that more than 90% of individuals with MEN1 mutation stand the risk of developing 1 or more signs of MEN1.

  • Germline mutations-alterations of the body’s egg or sperm cells, hence joining with the DNA of most cells through hereditary-in the cyclin-dependent kinase inhibitors,  which regulate cell growth.

Symptoms of MEN1

The symptoms of MEN1 varies but some predominant signs include:

  • Tiredness.
  • Pains in the bone.
  • Kidney stones.
  • Ulcers of the stomach or intestine.
  • Broken bones.
  • Depression.
  • Abdominal pain and non-specific aches and pains.
  • The over-production of vasoactive intestinal peptide causes severe watery diarrhea muscle weakness, and palpitations, resulting from low blood potassium.

Complications associated with MEN1

There are certain conditions associated with MEN1. They include:

  • Familial isolated hyperparathyroidism.
  • Hereditary hyperparathyroidism-jaw tumor syndrome.
  • MEN2 and MEN4
  • Von Hippel-Lindau syndrome.
  • Carney complex and Zollinger-Ellison syndrome.

When the excess hormone is secreted into the bloodstream, it could lead to the following complications:

  • Hyperparathyroidism
  • Hyperprolactinemia
  • Acromegaly
  • Cushing’s syndrome
  • Hypoglycemia 
  • Hyperglycemia 
  • Carcinoid syndrome.

Diagnosis of MEN1

It can be diagnosed if one is experiencing at least two of these tumors namely:

  • Parathyroid tumor
  • Pancreatic neuroendocrine tumor
  • Or even a pituitary gland tumor.

Also, it can be diagnosed through:

    • The medical record of the family traced to the presence of MEN1 
    • Genetic testing for mutations.
  • Blood tests to ascertain hormonal levels such as prolactin, insulin-like growth factor,  glucagon, etc.
  • Calcium level test.
  • Scans such as computerized tomography scan, magnetic resonance imaging (MRI), etc, are also done to locate the tumors.
  • Check for signs of excess hormones.

Treatment of MEN1

Since MEN1 involves tumors, steps are taken either to remove it or suppress its growth and these steps are applied based on the tumor or tumors present. Such treatment for MEN1 includes the following:

  • Medications that suppress the growth of such tumors.
  • Surgery as it is needed.
  • Somatostatin analog and growth hormone antagonists can be employed.


What happens when MEN1 is left untreated?

When MEN1 is left untreated, could result in osteoporosis–broken bones and kidney stones. Although, people with MEN1 can develop parathyroid cancer.

How common is multiple endocrine neoplasia type 1?

MEN 1 is a rare genetic condition that has been estimated to affect between 1 in 10,000 to 1 in 30,000 people; both men and women are affected. Although, the age at which people with MEN1 begin developing tumors varies and hence, not predictable just based on family history only.

What are the side-effects of the treatment?

After the surgery e.g parathyroid, calcium levels in the blood will reduce (hypocalcemia), causing tingling sensations in the hands and the face. Also, muscular spasms may be severe. This is managed using life-long supplements of activated vitamin D and calcium to aid boost normal healthy blood calcium levels.

Are there other tumors associated with MEN1 that are not Endocrine?

Non-endocrine tumors seen in MEN1 include:

  • Facial angiofibroma, a condition in which  a tumor of blood vessels and fibrous tissue is involved
  • Collagenoma, which involves a flesh-colored tumor on the skin.
  • Meningioma and ependymoma, which are both tumors from nervous system tissue and are rare.

Is MEN1 cancerous?

Most tumors are benign-small and not cancerous, although some risk of it leading to cancer is present, it is negligible.

The information provided in this blog is for educational purposes only and should not be considered as medical advice. It is not intended to replace professional medical consultation, diagnosis, or treatment. Always consult with a qualified healthcare provider before making any decisions regarding your health. Read more